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Commit 3f4a0f3c authored by Arthur Hung's avatar Arthur Hung
Browse files

Fix potential exception while pressing volume up and volume down 

When enabled a11y service, it would intercept key events and forwards
them to accessibility manager service.
This CL added the synchronized mechanism in KeyCombinationManager to
prevent it access the conflict state because
'interceptKeyBeforeDispatching' and 'interceptKeyBeforeQueueinging' are
called from different threads.

Bug: 209939290
Test: A11y CTS and unit tests.
Change-Id: I7adb70d21128340c5519a6c72cb4d732c0bbba43
parent 5a2d06b5

services/core/java/com/android/server/policy/KeyCombinationManager.java

+31 −12
Original line number Diff line number Diff line
@@ -17,11 +17,13 @@ package com.android.server.policy; 


import static android.view.KeyEvent.KEYCODE_POWER;



import android.os.Handler;

import android.os.SystemClock;

import android.util.Log;

import android.util.SparseLongArray;

import android.view.KeyEvent;



import com.android.internal.annotations.GuardedBy;

import com.android.internal.util.ToBooleanFunction;



import java.io.PrintWriter;
@@ -35,13 +37,18 @@ public class KeyCombinationManager { 
    private static final String TAG = "KeyCombinationManager";



    // Store the received down time of keycode.

    @GuardedBy("mLock")

    private final SparseLongArray mDownTimes = new SparseLongArray(2);

    private final ArrayList<TwoKeysCombinationRule> mRules = new ArrayList();



    // Selected rules according to current key down.

    private final Object mLock = new Object();

    @GuardedBy("mLock")

    private final ArrayList<TwoKeysCombinationRule> mActiveRules = new ArrayList();

    // The rule has been triggered by current keys.

    @GuardedBy("mLock")

    private TwoKeysCombinationRule mTriggeredRule;

    private final Handler mHandler = new Handler();



    // Keys in a key combination must be pressed within this interval of each other.

    private static final long COMBINE_KEY_DELAY_MILLIS = 150;
@@ -109,6 +116,12 @@ public class KeyCombinationManager { 
     * Return true if any active rule could be triggered by the key event, otherwise false.

     */

    boolean interceptKey(KeyEvent event, boolean interactive) {

        synchronized (mLock) {

            return interceptKeyLocked(event, interactive);

        }

    }



    private boolean interceptKeyLocked(KeyEvent event, boolean interactive) {

        final boolean down = event.getAction() == KeyEvent.ACTION_DOWN;

        final int keyCode = event.getKeyCode();

        final int count = mActiveRules.size();
@@ -154,7 +167,7 @@ public class KeyCombinationManager { 
                        return false;

                    }

                    Log.v(TAG, "Performing combination rule : " + rule);

                    rule.execute();

                    mHandler.post(rule::execute);

                    mTriggeredRule = rule;

                    return true;

                });
@@ -169,7 +182,7 @@ public class KeyCombinationManager { 
            for (int index = count - 1; index >= 0; index--) {

                final TwoKeysCombinationRule rule = mActiveRules.get(index);

                if (rule.shouldInterceptKey(keyCode)) {

                    rule.cancel();

                    mHandler.post(rule::cancel);

                    mActiveRules.remove(index);

                }

            }
@@ -181,32 +194,38 @@ public class KeyCombinationManager { 
     * Return the interceptTimeout to tell InputDispatcher when is ready to deliver to window.

     */

    long getKeyInterceptTimeout(int keyCode) {

        synchronized (mLock) {

            if (forAllActiveRules((rule) -> rule.shouldInterceptKey(keyCode))) {

                return mDownTimes.get(keyCode) + COMBINE_KEY_DELAY_MILLIS;

            }

            return 0;

        }

    }



    /**

     * True if the key event had been handled.

     */

    boolean isKeyConsumed(KeyEvent event) {

        synchronized (mLock) {

            if ((event.getFlags() & KeyEvent.FLAG_FALLBACK) != 0) {

                return false;

            }

            return mTriggeredRule != null && mTriggeredRule.shouldInterceptKey(event.getKeyCode());

        }

    }



    /**

     * True if power key is the candidate.

     */

    boolean isPowerKeyIntercepted() {

        synchronized (mLock) {

            if (forAllActiveRules((rule) -> rule.shouldInterceptKey(KEYCODE_POWER))) {

                // return false if only if power key pressed.

                return mDownTimes.size() > 1 || mDownTimes.get(KEYCODE_POWER) == 0;

            }

            return false;

        }

    }



    /**

     * Traverse each item of rules.